Emergence of immunotherapy as a novel way to treat hepatocellular carcinoma

Figure 5 Mechanism underlying immune functions of CTLA-4 and PD-1-PD-L pathways. A: CTLA-4 has a higher binding affinity to CD80/CD86 than the co-stimulatory signal molecule CD28. As a consequence, CTLA-4 competitively antagonizes the stimulatory signal, which the interaction between CD80/86 and CD28 generates at the priming phase of T cells. B: The PD-L1/L2-PD-1 interaction interferes with T cell activation signals in the effector phase.